button tells me it's "Out of stock" when it isn't on mobile

Hi

I'm trying to setup marketpress on a mobile site but I have a problem. When you click on "Add to Cart" it shows the load animation, then "added to cart" appears and then it fades out again and "Out of Stock" fades in (it's in stock so this is not good).

This only seems to be a problem with mobile devices, I've tried it on an IOS and Android device and they both have the same problem. I thought it might be a webkit thing so I tried it in safari and it worked as it should.

Please help, I need to have this ready pretty soon.

Regards

Daryl